Differentiation between normal residence performance and landslide-related distress in the evaluation and treatment of slope instability in southern California
Hugh S. Robertson, Robert A. Hollingsworth, 1992. "Differentiation between normal residence performance and landslide-related distress in the evaluation and treatment of slope instability in southern California", Landslides/Landslide Mitigation, James E. Slosson, Arthur G. Keene, Jeffrey A. Johnson
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The evaluation and repair of hillside properties damaged by slope instability presents a challenging problem for the geotechnical professional. An increasing number of residential distress evaluations are being requested by homeowner insurance companies to resolve earth-movement claims. Early recognition of instability is essential to the successful mitigation of the hazard. Thorough observation of structural distress, experience, and an understanding of construction are needed to differentiate typical distress from subtle distress associated with the initiation of slope instability. Other soil-related processes cause distress similar in appearance to major slope movement, and complicate recognition of an impending hazard.
Property-line limitations and reluctant neighbors hamper site and neighborhood reconnaissance. High costs and physical constraints limit the subsurface exploration, which is critical to determining the mechanics of movement. Conventional exploration techniques are aided by modern instrumentation and detailed site monitoring to define probable causes. Selection of reasonable repair methods and stabilization devices de-pends on the limits of the failing mass and whether instability is associated with failure along a predetermined defect or through an inherently weak mass. Continued monitor-ing from recognition through stabilization helps verify the causes of instability, the design scheme, and the success of the treatment. Repairs are effective if the factor of safety is sufficiently increased by common and economical construction techniques in a timely manner.
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Provides a variety of case histories, methodology to help identify, quantify, and mitigate landlsides, and legal cases affecting engineering geology. Part I provides basic information to aid in assessing geologic hazards related to compound landslides, surficial slope failures, and causes of distress to residential construction. Includes changes in the law relating to geologic investigations and disclosure of geotechnical information. Part II is a cross section dealing with recent significant landslides related to a single storm, intense rainfall, possible errors in the identification of and development on an existing or paleolandslide, and the use of pumping wells and horizontal drains to dewater slope failures. Also discusses how proper installation and use of drains prevent paleolandlsides from causing damage to modern facilities.